5 things it takes to be a great secretary of state — and is Hillary one?

U.S. Secretary of State Hillary Clinton checks her PDA upon her departure in a military C-17 plane from Malta bound for Tripoli, Libya on Oct. 18, 2011. (Kevin Lamarque/Reuters) Hillary Rodham Clinton is preparing to leave office after President Barack Obama’s second inauguration on Jan. 20. So, how did she stack up among those who’ve held the job, and do her potential successors fit the mold for greatness? But first, what makes a great secretary of state? It's good to …